Hole lapping machine



March 3o, 194s.y A, M RAKE y 2,438,695

HOLE LAPP ING MACH I NE Filed Jan. `29, 1944 2 sheets-shawl l 5 v I, l t@ N 1 A I l \1\\ l q l @z Y l 'Q I x I I y i 'x l 4 I w i I IMarCh3O, 1948. M DRAKE I' 2,438,695

HOLE LAPPING MACHINE Filed Jan. 29, 1944 2 Sheets-Sheet 2 INVENToR. .diffe/2M Dra/17 Patented Mar. 30, 1948 UNITED STATES PATENT OFFICE vHOLE LAPPING MACHINE Alden M. Drake, West Hartford, Conn., assignor to Niles-Bement-Pond Company, West Hartford, Conn., a corporation of New Jersey Application January 29, 1944, Serial No. 520,25'l

v 6 Claims. 1 Y

This invention relates to lapping machines and particularly to a machine for lapping internal cylindrical surfaces to precision dimensions.

An objectl of the invention is to provide a machine for automatically reciprocating a work piece having an internal surface to be lapped over the surface of a lapping tool which may be rotated simultaneously with the reciprocations of the work piece. Y

Another object of the invention is to provide a holder for the work piece being lapped which will allow the work piece to t freely over the lapping surface of the tool and adjust itself V,thereon in any direction during the lapping operation.

Another object of the invention is to provide the work holder with means indicating the effectiveness or amount of lapping being done on the work piece during the lapping operation.

And finally it is an object of the invention to provide impact vmeans manually applied under controllable conditions to slightly increase the diameter of the lapping tool during the lapping operation.

With the above and other `objects in View the invention includes the features of construction and operation set forth in the following specification and illustrated in the accompanying drawings.

In theaccompanying drawings annexed hereto and forming a part of this specification, I have shown the invention embodied in a hole lapping machine for annularly grooved rolls of small size but it will be understood that the invention can be otherwise embodied and that the drawings are not to be construed as defining or limiting the scope of the invention, the claims appended to .this specification being relied upon for that purthe impact means for forcing the lap axially' along its arbor to adjust the size of the lapping surface during the lapping operation.

Fig. 4 is a detail view of parts shown in Fig. 3 taken from below.

Fig. 5 is a plan View of a form -of holder for the work pieces being lapped, and

Fig. 6 is a central sectional view in elevation taken on the plane of line 5 5 of Fig. 5.

In the `above mentioned drawings there has been shown butk one embodiment of the invention which is now deemed preferable, but it is to be understood `that changesand modifications may be made within the scope of the appended claims without departing from the spirit of the invention.

In lapping holes in rolls for screw thread gages by means of which they are supported in the gage frame it is essential that the holes 'be of uniform diameter from end to end and without taper or bell-mouthing. The rolls must fit their arbors closely and from end to end so that the rolls will not tilt on their arbors but will rotate smoothly on a fixed axis. Heretofore precision lapping of internal cylindrical holes has been done manually, the work piece being held manually in position upon a rotating lapping tool and slowly recprocated back and forth. The lap usually comprised a split cast iron sleeve fitted over a slightly tapered arbor. To expand the lapping surface of the lap the sleeve was forced axially along the tapered 'arbor'.

The present invention provides mechanical means to reciprocate the 'work piece over the lap during rotation thereof and a novel holderv or mounting means to hold the work piece in a manner to permit the Work piece to adjust itself upon the lappingsurface. Also means are provided for forcing the expansible lap predetermined slight amounts axially during the lapping operation to slightlyincrease its diameter.

Briefly and in its preferred aspect the invention may include thefollowing principal parts: First, aspindle adapted to be rotated by any appropriate means and havingv means at its forward end to support a lapping `tool extending ax ially from the spindle; second,` a reciproc'able member adjacent the rotatably mounted spindle, there preferably being hydraulic or other form of operating means to reciprocate this member and also to vary'the speed and distance of travel of this member; third, 3,. work supportingr member mounted on and actuated by this reciprocable member permitting adjustment of the work piece in any direction upon the lapping surface; fourth, a plunger alined with the lapping spindle and adapted to be resilientlyretracted and forced forward to engage the lapping tool so that the position of thel lapping tool on its spindle may be adjusted axiallyto slightly increase its diameter.

Referring more in detail to the figures of the drawing and first to Fig. 1, I provide a spindle ID adapted to be driven by a bevelgear H' on a short shaft'` I2 in .alinement with the spindle I0 3 and which in turn may be driven through any suitable connections such as a driving bevelgear I3 connected by means not shown to a suitableY source of power. To conveniently start and stop rotation of the spindle I a friction clutch I4 may be provided between the spindle I9 and the driv-Y ing shaft I2. This clutch I4, as shown, may be maintained with its members normally in engaged Vand connections to engage a ange on one ofthe clutch members.

The forward end of the spindle I0 is provided with a chuck I8 within which may be` mounted a lapping tool arbor I9. AsV this chuck I8 may Y retractable member 23Jsofthat byoscillation of be of any suitable form permitting quick and convenient change of lapping tool arbors, it is not thought that further descriptioifwill be needed. It will suffice to state that the lapping tool comprisesvan arbor I9 having aslightly tapered'surface over which is ltted'an expansible lapping member preferably in the form of an elongated sleeve slotted along one side as shown, the outer surface of this member being cylindrical. By adjustment of this member 20 axially along its tapered arbor I9 the diameter of 'its outer cylindrical surface may be slightly varied during the lapping operation.

In order to adjust the position of the lapping member 2U upon its arbor I9 as required during the lapping operation, impact means are provided which: may be actuated manually to deliver a carefully regulated blow upon the end faceof the split sleeve forming lapping tool 20 to'force this member axially on'its arbor I9 a slight but predetermined distance. To effect this impact adjustmentof thelap 20 a bracket 2| is mounted upon the base of the machine having a plunger 22 therein disposed accurately in alinement with the spindle III and arbor I9. This plunger 22 is Y mounted within the retractable member 23 within the bracket 2| and is normally forced toward the lapping spindle by` a helical spring 24. By manually retracting this member 23 which compressesthe spring 24, then upon release of the member 23 theplunger 22 will be forced forward ly and its endface willbe brought into contact with and force the lapping tool 20 axially along its arbor I9. To adjust the axial position of the plunger 22 so that its end face will strike the end of rrlapping sleeve' 29, the plunger 22 may be threaded throughout the major portion of its length, the threads of which engage a retractable detent 25. The plunger 22 may therefore, by ro'- tation, be accurately adjusted so that when forced forward it will strike the lap 20. Also by disengaging the detent 25 the plunger 22 may be quickly moved any vdistance in either direction. The forward orV striking end of this plunger 22 may be provided with an adapter 26vrotatable within the plunger 22 and recessed to lit over the end rof the lapping arbor I9 and directly engage the front face of the sleeve forming the lap.

InV order to control the blow effected by this plunger 22, means are provided vto adjust the pressure of the helical spring 24. As `will be seen in Fig. 3,the helical spring is housed in the bracket 2| Within a suitable recess. The forward end of the spring 24 bears against the head of a bolt 2T extending through the bracket 2| and through a portion of'theV retractable member 23'.` The Vouter .end of this Ybolt 21 isV threadedY and is en 4 gaged by a suitable manual adjusting nut 28. By rotation of this nut 28. the pressure of the helical spring 24 holding the retractable member 23 in its forward position may lbe widely varied. In order to control the delivery of the blow ofthe plunger 22 against the lap 29 a hand lever 29l is provided having a projection or latch 29av adapted to engage a depending portion of the this handle 29 the projection will be disengaged from the depending portion of the retractable member 23 after a predetermined movement. This will release the retractable member 23 for forwardmovement under the pressure of the heli cal spring 24.- To adjust the plunger 22 Vso that it will contact the end face of the lapping tool and advance thistool a'predetermined distance when released it is only necessary to rotate the plunger 22 within the retractable member 23.

The particular and 'preferred means to retain the work piece W whilebeingoperatedon is shown mosty clearly in Figs. 5 and 6.v vIt'will be' seen that the member actuating this hol'der is in thejform ofY a bracket 3| havinga-.barI orY rod 44 adjustab-ly fixed thereto, the .barl44 being reciprocated by meansvpresently to be described. This bracket member 3| has -a transverse horizontal hole thereinengaged by a c ylindricalprogjection 32 on the work piece holding `member. 39 so that this holder mayV oscillate about the'axis of this projection. Extending laterally from member 39 are notched arms 33` extendingfabovefand below theaxs of the lapping tool 295sothatpro1- jections. 35 on -thework-piece clamping :member 3 4' mayV engage the `notches andbe retained therein by la swivel member 33 having arms .f1t-

ting against the projections on vthe work piece clamping member. Preferably, spring, means 3l are provided for normally retaining the swivelling member 36in its work piece retaining; position, the tension being, adjustable by rotation of. one end of a helical spring, the opposite' end of'which is attach'ed to the shaftY or spindle 38on:.which this swivelling member 36 Vvis rotatably supported.

Also a lever or arm 39 may beprovided permit?- ting manual disengagement or oscillation of `this member so that theclamping'imember :3i-'and work piece W may be convenientlyplaced inor withdrawnv from the holder 39. Byfumeans" of the swivelling member 36 being springheld in position to engage oppositely extending'arms'on the work clamping member 35 vwhen thetraversing movement of the work piece W along the-.lap 29 is reversed,V the drag ofthe lap 2liy overthe work piece W willV force the projections V35 to the opposite Vsides of the notches in projections 33 causingV the swivelling member to Iswing van amount dependent upon the drag when the move"- ment of the holder 39 istowardthe spindle I9.

By watching the swivelling actionof this member 36 th'e amount of lapping action' can be dc,.- termined and when movement" of the'swive'llin'g member `does not occur it-indicates that-no lapping isv being effected. To holdthe `work piece,

which in the form of the invention showlf'l` inV the drawing isa small threadedroll, the clamping member 31 surrounds yand isiin` clamping en:-

gagement with itsouter periphery.A From'th'e top and bottom Vofy this clamping member 34 extend the radial arms carrying the projections 35 which engage within the notchesin the holding and reciprocating member 3|);

In operation the spindle I9' carrying'thelap 29 is rotated at any d'esired'speed; if desired, the spindle may be rotated a'gf'ew revblutionsinreaoh direction but may be rotated continuously in one direction without losing the advantages of the present invention. By periodically reversing rotation of this spindle lapping will take place equally during rotating in either direction of rotation, these reversals of rotation also providing for an even distribution of the lapping compound. The lapping operation, therefore, is speeded and rendered more uniform from end to end of the work piece. During this rotation of the spindle I the work holding member 30 is reciprocated through variable distances regulated by the adjustable stops 40 on the valve shaft 4l directly above the operating piston 42. As any standard type of mechanism may be employed for these reciprocatory movements, no further description of them is thought to be necessary other th'an to say that the piston 42 is moved hydraulically within a cylinder 43 and reciprocates the member 30 and the rod 44 attached thereto between limits determined by the position of stops 40,

What I claim is:

1. In a lapping machine, a holder comprising a clamping member engaging a work piece, coaxial alined projections extending from opposite portions of said clamping member, a yoke member having recesses enga-ging said projections whereby said work piece may swivel about the axis of said projections, and a' projection on said yoke member extending at right angles to the axis of said recesses whereby said work piece may be reciprocated by means engaging said last named projection.

2. In a lapping machine, a holder comprising a clamping member engaging a work piece, coaxial alined projections extending from opposite portions of said clamping member, a yoke member having recesses engaging said projections whereby said work piece may swivel about the axis of said projections, and a projection on said yoke member extending at right angles to the axis of said recesses about which said yoke member may swivel whereby said work piece may be reciprocated by means engaging said last named projection while being free to adjust itself about axes normal to each other.

3. In a lapping machine, a holder comprising a clamping member engaging a work piece, coaxial alined projections extending from opposite portions of said clamping member, a yoke member having recesses engaging said projections whereby said work piece may swivel about the axis of said projections, means to retain said projections within said recesses, and a projection on said yoke member extending at right angles to the axis of said recesses about which said yoke member may swivel whereby said work piece may be reciprocated by means engaging said last named projection while being free to adjust itself about -axes normal to each other.

4. In a lapping machine, a holder comprising a clamping member engaging a work piece, coaxial alined projections extending from opposite portions of said clamping member, a yoke member having recesses engaging said projections whereby said work piece may swivel about the axis of said projections, means to retain said projections within said recesses, and a projection on said yoke member extending at right angles to the axis of said recesses, and a reciprocating member rotatably engaging said last named projection whereby said work piece may be reciprocated by means engaging said last named projection,

5. A lapping machine comprising in combination, a base having a lapping tool rotatable therein, a piston reciprocable in a direction parallel to the axis of rotation of said lapping tool, a holder comprising a clamping member engaging a work piece on said lapping tool, co-axial alined projections extending from opposite portions of said clamping member, a yoke member having recesses engaging said projections whereby said work piece may swivel about th'e axis of said projections, and a projection on said yoke member extending at right angles to the axis of said recesses whereby said work piece may be reciprocated over said lapping tool by said piston.

6. In a lapping machine, a work holder comprising a clamping member engaging a work piece, a yoke member mounting said clamping member for free adjustment about an axis normal to the axis of the work piece being lapped, said yoke member being mounted for free adjustment about an axis normal to the axis of adjustment of the clamping member and the axis of the work piece being lapped, and means to reciprocate the work piece, cl-amping member and yoke member axially over a lapping tool.

ALDEN M. DRAKE.

REFERENCES CITED The following references are of record in the le of this patent: 

